Solid yellow lines on the road indicate:

Yellow lines separate traffic moving in opposite directions. A solid yellow line on your side of the centerline means passing is prohibited from your side — it is unsafe to cross into the oncoming lane to pass. A broken yellow line on your side means passing is permitted when the oncoming lane is clear. Two solid yellow lines (a double solid) means passing is prohibited in both directions. White lines separate lanes moving in the same direction; a broken white line means lane changes are permitted, and a solid white line discourages but does not always prohibit lane changes (laws vary). Markings are placed by traffic engineers based on sight distance and road geometry — they exist to keep you alive.